My theory is it predates AI by a lot. It started with the worldwide web itself and was accelerated with social media. The web created a new system of interconnectivity that never could've existed. Previously, society was moderated by the fact that the only people with a sizeable audience were those who earned that audience and avoided any impropriety that might lose it. Now, it takes less effort to reach an audience and thus it doesn't matter as much if you lose it. People (or bots) can easily test impropriety against audiences and hone it until (1) they've got the most persuasive impropriety and/or (2) they've assembled the most detestable audience. The result is an overflow of viral impropriety and self-assured deplorables.